Phase detector

Abstract

A phase detector for monitoring the presence, sequence and polarity of each phase line for a three-phase power input and indicating when a phase is missing or out of sequence.

I claim: 
     
       1. A phase detector for monitoring a first phase line, a second phase line and a third phase line for a three-phase line power input in which each phase has a positive polarity region and a negative polarity region occurring in a given sequence which comprises: first, second and third cross-over detecting means for deriving respective first, second and third activator signals in the presence of the transition of the first, second and third respective phases between said regions;   first, second and third activators having activator inputs connected to said first, second and third cross-over detecting means respectively, having line phase inputs connected to the next adjacent phase lines of said given sequence, and having activator ouputs;   said first, second and third activators alternatively having a first line phase condition at their line phase inputs corresponding with the presence of the next adjacent phase of said given sequence thereof or a second line phase condition at their inputs corresponding with the absence of the next adjacent phase of said given sequence thereof;   said first, second and third activators being actuable in response to said first, second and third activator signals to provide first, second and third activator output signals at their respective outputs corresponding to the line phase condition at the first, second and third respective line phase inputs thereof; and   first perceptible indicating means connected to said first, second and third activator outputs which is activated when all of said first, second and third respective activator outputs have said first line phase condition.   
     
     
       2. The phase detector of claim 1 in which: said detector includes second perceptible indicating means which is activated when one of said first, second and third respective outputs has said second line phase condition.   
     
     
       3. The phase detector of claim 1 in which: said detector includes a fourth activator means responsive in the presence of a select line phase condition at any of the first, second or third phase lines for providing an enable output to said first perceptible indicating means.   
     
     
       4. The phase detector of claim 2 in which: said detector includes a fourth activator responsive to the presence of a select line phase condition at any of the first, second or third phase lines for providing an enable output to said second perceptible indicating means.   
     
     
       5. The phase detector of claim 1 in which: said detector includes an energy storage device which causes said first perceptible indicating means to have a steady state output.   
     
     
       6. The phase detector of claim 3 in which: said fourth activator means is responsive in the presence of a select line phase condition at any of the first, second or third phase lines to provide an enable output to said first, second and third cross-over detecting means.